A new landmark study on the effects of the morphine drug shows that the even after the residue had worn off the system there is still a persistent effect of the drug on the brain. It was found that a single dose actually distorted the neural pathways that control the sensation of craving.
A single dose of morphine injected into the rat was still low on inhibition even after the drug had left their system. The result of the research, conducted at the Brown University, would now help to understand the drug addiction in the humans and even find an antidote for it.
Julie Kauer, a professor of molecular pharmacology, physiology and biotechnology at Brown said that "What we have found is that the inhibitory synapses can no longer be strengthened 24 hours after treatment with morphine, which suggests that a natural brake has been removed," "By shutting off the natural ability to strengthen connections that inhibit pleasure, the brain may be learning to crave drugs," The excitatory synapses are growing stronger over time with increased activity.
Kauer says there are two kinds of neurons one that excites the nerve connection and the second that restrains or depresses them. She says "if inhibition is reduced, you get runaway excitability".
This aspect can have dangerous overtones for abuse if drugs like heroin or cocaine invoke similar responses. According to Kauer "addiction is a form of pathological learning in which the brain has created a rewards system for something that is harmful to the body. I would not call it damage — the circuit is working the way it should. But it has been remodeled in a maladaptive way,"
The long lasting effect of the drug is the reason why the craving for the drug is so hard to overcome.
A pharmaceutical treatment to reduce the effect of strong craving could help those fighting addiction resisting the temptation of relapse.